The present invention relates generally to semiconductor device manufacturing and, more particularly, to preventing oxygen absorption into high-k gate dielectric layers of silicon-on-insulator (SOI) based finFET devices.
Fin field effect transistor (finFET) technology is an emerging technology that provides solutions to metal oxide semiconductor FET (MOSFET) scaling problems at and below the 45 nanometer (nm) node. A finFET is a MOSFET that is formed on a semiconductor fin. For example, a finFET includes at least one narrow (e.g., <10 nm wide) semiconductor fin gated on at least two opposing sides of the fin. FinFET structures are advantageously formed on a semiconductor (e.g., silicon)-on-insulator (SOI) substrate, because of the precise control of the fin height, which is determined by the substrate silicon thickness, as well as the ease of electrical isolation by shallow trench isolation structures.
Another area of advancing technology that provides enhanced performance for MOSFET scaling problems is the development of so-called “high-k gate” dielectric materials. High gate leakage current of nitrided silicon dioxide and the depletion effect of polysilicon gate electrodes limit the performance of conventional silicon oxide-based gate electrodes. High performance devices for an equivalent oxide thickness (EOT) less than 1 nm require high-k gate dielectric materials and metal gate electrodes to limit the gate leakage current and provide high on-currents. More specifically, high-k gate dielectric materials refer to dielectric metal oxides or dielectric metal silicates having a dielectric constant that is greater than the dielectric constant of silicon oxide (i.e., greater than about 3.9).